Informal caregivers (those who provide unpaid care for an ill or disabled family member or friend) play a critical role in the care of aging and disabed individuals in the US. As the number of individuals requiring informal care increases, greater numbers of caregivers will be at risk of poor health outcomes associated with caregiving. It is therefore vital to understand the pathways by which caregiving may adversely impact caregiver health, so as to inform interventions and policies that will protect caregivers and their families. In order to achieve this goal, this study seeks to determine if and to what extent the perception of strain due to caregiving explains the association between characteristics of the caregiving experience and caregiver health on both the subjective and physiological level. Using a population-based sample of adults ages 21 to 74 from the state of Wisconsin, the specific aims of this study are to: 1) compare caregivers and non-caregivers on perceived stress and mental and physical health-related quality of life, and evaluate if disparities exist in these outcomes; 2 determine the impact of caregiving characteristics (including duration of caregiving, hours per week of care provided, relationship with the care recipient, disability or illness of the care recipient, and co-residence with the care recipient) and caregiver strain on health-related quality of life; and 3) determine the association between caregiving characteristics, caregiver strain, and telomere length, a biological marker of the physiological impact of caregiving stress. Generalized additive models will be used to account for potential non-linear relationships in this study, and more accurately evaluate these relationships. This study is directly in line with the mission of the National Institute on Aging to support interdisciplinary research into the nature of aging and the aging process. Ultimately this research will provide evidence of how best to protect the health and quality of life of caregivers and those for whom they care. The information gained from this study will lead to better identification of high-risk caregivers, and will prove critical to the development of effective and sustainable interventions and policies that will prevent or reduce caregiver strain and subsequent poor health outcomes. This will be essential in improving the health and quality of life caregivers and their families. PUBLIC HEALTH RELEVANCE: This study will add to the understanding of the how caregiving may lead to poor health-related quality of life and accelerated cellular aging. This information will be important for future research studies and may lead to interventions that will improve health outcomes and increase the healthy-active years of life for caregivers and their families.